Conventionally, the emulsification and dispersion of functional oil based agents or functional granules into water were conducted by selecting a surfactant according to the required HLB of the functional oil based agents or properties of granule surface. In addition, the required HLB value of the surfactant used as an emulsifier had to be chosen distinctively according to whether O/W type emulsions or W/O type emulsions were to be formed; moreover, the thermal stability and the long term stability were not sufficient, and therefore, various different types of surfactants also had to be used. (ref. Non-patent document 1-4).
However, surfactants are not very biodegradable and produce a gas, thus causing serious problems of environmental pollution. Furthermore, although physicochemical emulsification methods such as the HLB method, phase inversion emulsification method, phase inversion temperature emulsification method, gel emulsification method, etc., have generally been used as conditioning methods for emulsified preparations of functional oil-based agents, in each case, because an action to thermodynamically stabilize the system by reducing the surface energy of the oil/water is the base of the emulsification conditioning process, the emulsification method was therefore accompanied by extremely complicated and extensive effort to select the most suitable emulsifier, and in any case, when a variety of oils had been mixed together, it was almost impossible for these oils to be stably emulsified.
For this reason, Patent Document 1 proposes an emulsifier comprising, as a main component, a vesicle composed of an amphiphilic agent with self-organization ability or a nanoparticulated biopolymer, and an emulsification method using the emulsifier. In this emulsification method, the emulsifier is attached to an oil/water interface to form a three-phase structure of a water phase, an emulsifier phase, and an oil phase. The method is thus referred to as a so-called three-phase emulsification method.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2006-239666
Non-patent document 1: “Emulsion Science” edited by P. Sherman, Academic Press Inc. (1969)
Non-patent document 2: “Microemulsions-Theory and Practice” edited by Leon M. Price, Academic Press Inc. (1977)
Non-patent document 3: “A technique of Emulsification and Solubilization” by Atsushi, Tuji, Kougakutosho Ltd. (1976)
Non-patent document 4: “Development Technique for Functional Surfactants” CMC Publishing Co., Ltd. (1998)